Side seal assembly for rotary piston mechanisms

ABSTRACT

The side seal assembly for sealing the interstices between each of the side faces of a rotary piston and the adjacent end wall surfaces of the housing of a rotary piston mechanism and isolating the working chambers of the mechanism from each other and the crankshaft area comprises a plurality of abutting side seal strips disposed in grooves in the rotor side face located near the peripheral surfaces of the rotor and extending between each of the apex portions of the rotor. Each side seal strip is constructed and arranged to abut, along its length, the end wall housing surface and to sealingly abut, at one end, the side of an adjacent side seal strip at a point near, but spaced from, one of the apex seal means and, at the opposite end, capable of abutment against another of the apex seal means of the rotor.

United States Patent [191 Griffith SIDE SEAL ASSEMBLY FOR ROTARY PISTON MECHANISMS [75] Inventor: Michael J. Griffith, Kenosha, Wis.

[73] Assignee: Outboard Marine Corporation,

Waukegan, Ill.

[22] Filed: Apr. 25, 1972 [21] Appl. No.: 247,451

[52] 11.8. C1 418/120, 418/113, 418/142 [51] Int. Cl. F0lc 19/00 [58] Field of Search 418/113, 120, 122, 418/123, 142,179

[56] References Cited UNITED STATES PATENTS 3,120,815 2/1964 Froede 418/123 3,130,900 4/1964 Schlor 418/122 3,142,439 7/1964 Froede.... 418/122 3,168,237 2/1965 Paschke 1. 418/122 3,180,562 4/1965 Bentele... 418/142 3,193,189 7/1965 Rastogi... 418/122 3,302,622 2/1967 Jones 418/113 3,535,061 10/1970 Yamamoto 418/142 9/1971 Schmidt 418/142 7/1972 Larriwaga et a1 418/142 Primary Examiner-C. J. I-lusar AttorneyArthur Frederick et a1.

[5 7] ABSTRACT The side seal assembly for sealing the interstices between each of the side faces of a rotary piston and the adjacent end wall surfaces of the housing of a rotary piston mechanism and isolating the working chambers of the mechanism from each other and the crankshaft area comprises a plurality of abutting side seal strips disposed in grooves in the rotor side face located near the peripheral surfaces of the rotor and extending between each of the apex portions of the rotor. Each side seal strip is constructed and arranged to abut, along its length, the end wall housing surface and to sealingly abut, at one end, the side of an adjacent side seal strip at a point near, but spaced from, one of the apex seal means and, at the opposite end, capable of abutment against another of the apex seal means of the rotor.

11 Claims, 3 Drawing Figures SIDE SEAL ASSEMBLY FOR ROTARY PISTON MECHANISMS This invention relates to rotary piston mechanisms of the type disclosed in the U. S. Pat. to Wankel et al No. 2,988,065, and, more particularly, to side seal assemblies carried by the rotary piston of such engines to seal the interstices between the piston side faces and the end wall surfaces of the housing of such mechanisms.

BACKGROUND OF THE INVENTION In rotary piston mechanisms of the aforesaid type, the working chambers defined by each of the peripheral surfaces of the rotary piston or rotor and the walls of the housing within which the rotor rotates must be maintained in fluid tight isolation from each other and the crankcase area for optimum operating efficiency. As evidenced'by the following United States patents, a continual effort has been exerted to improve the fluid seal between the rotor and housing:

In all of the aforementioned patents, the sealing means comprise apex seals, which are located in a groove formed at the apices of the rotor and project thereform to engage the trochoidal surface of the housing and side seal assemblies which coact with the apex seals. Each of the side face seal assemblies include side seal strips carried in grooves in the side faces of the rotors so as to extend therefrom into engagement with the surface of the housing end walls and an apex pin which is located at the juncture of the side seal strips and the apex seal. Each of the apex pins is slotted to receive a portion of an associated apex seal. The apex seals, apex pins and the side seal strips abuttingly cooperate to provide a substantially uninterrupted fluid sea] at each rotor side face. In these conventional side seal assemblies where the side seal strips abut at their ends the surface of the apex pins, as exemplified in the U. S. Pat. to Fisch, No. 3,134,600, or where one or both ends of each side seal strip is in a lap joint abutment with a wall or walls of the chordal notch or notches in the apex pin, as exemplified in the U. S. Pats. to Bentele, No. 3,033,180 and No. 3,180,562, accurate machining operations are required to insure that the wall or walls of the chordal notch or notches are in co-planar relation to the groove into which each of the strips are carried and the lengths of the strips are such as to effect their proper abutment against the apex pin. Also, the apex pin must be accurately machined to fit within its associated recess in the rotor side face and to insure that its longitudinally extending slot is in proper registry with the apex seal groove or slot to receive a portion of the apex seal therein. This requirement for accurate machining and assembly of the conventional side seal assemblies results in relatively high fabricating costs.

Accordingly, it is an object of this invention to provide a side seal assembly for a rotary piston mechanism which is capable of providing a substantially uninterrupted seal yet does not require a high degree of machining accuracy.

Another object of the present invention is to provide a side seal assembly for a rotary piston mechanism which assembly is inexpensive and easier to assemble than heretofore known side face sealing assemblies.

A further object of this invention is to provide an effective side seal assembly for a rotary piston mechanism in which the need for an apex'seal pin has been obviated.

SUMMARY OF THE INVENTION The invention therefore contemplates an improved side seal assembly for a rotary piston mechanism, which assembly coacts with the ends of the apex seals to provide a substantially uninterrupted seal between each of the rotor side faces and the adjacent housing end walls of the mechanism. The assembly comprises plural side seal groove means in the rotor side face extending between adjacent apex portions of the rotor and in which each side seal groove means is so constructed and arranged that it intersects another groove means in an area offset from the plane of the adjacent apex seal and, at the opposite end, intersects the apex groove in which an apex seal is carried. A side seal strip means is disposed in each of the plurality of side seal groove means and each is dimensioned so that it abuts, at one end, an adjacent seal strip means and, at the opposite end, terminating at the apex groove in the adjacent apex portion of the rotor.

In another embodiment the side seal groove means constitutes a pair of spaced grooves extending between adjacent apex portions. The outer grooves or grooves closest to the periphery of the piston are arranged as in the previously described embodiment. The inner grooves extend so that each seal strip disposed in the inner grooves abut, at one end, a seal strip in an outer groove and, at the opposite end, abuts a seal strip in an inner groove.

Obviously, the side seal assembly of this invention dispenses with the need for apex seal pins that conventional side face seal assemblies require.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be more fully understood from the following detailed description thereof, when considered in connection with the accompanying drawing, wherein two embodiments of the invention are illustrated by way of example and, in which:

FIG. 1 is a cross-sectional view through a rotary piston mechanism showing the rotor thereof having a side seal assembly according to one embodiment of this invention.

FIG. 2 is a view in cross-section of a rotary piston mechanism showing the rotor thereof in elevation and the side seal assembly according to another embodiment of this invention; and

FIG. 3 is a fragmentary, cross-sectional view taken substantially alongline 3-3 of FIG. 1, somewhat enlarged.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Now referring to the drawings and more particularly be employed as an internal combustion engine, expansion engine, compressor or pump. The mechanism has a housing 12 which comprises an intermediate wall 13 forming a trochoidal surface 14 and two end walls 15 (only one of which is shown) which abut opposite sides of the intermediate wall. The end walls 15 and intermediate wall 13 form a cavity within which a rotary piston or rotor 16 is supported for rotation on a shaft 18. The mechanism, as illustrated, may be a two-lobed cavity in which case the rotor 16 has opposite side faces 17 (only one of which is shown) and a three-sided peripheral configuration. The three flanks or peripheral wall surfaces 20 of rotor 16 converge to form three apex portions 22. The rotor 16 defines with the housing cavity three working chambers 24, 26 and 28 which, as rotor 16 rotates relative to the housing, successively expand and contract in volumetric size. To permit the mechanism to perform work efficiently, it is essential that each of the working chambers 24, 26 and 28 be maintained in as fluid tight isolation as possible from each other and the crankcase or shaft area 30. To this end, a sealing system is provided which comprises apex seals 32 located at the apex portions 22 of rotor 16 and side seal assemblies carried in the end faces of rotor 16. Each apex seal 32 is disposed in a radial slot 34 in the apex portion 22 and is biased outwardly thereof to engage the trochoidal surface 14 and the opposite housing end wall surfaces. The apex seals 32 may be of the construction such as disclosed in U. S. Pats. to Jones, No. 3,400,691 or Anderson, No. 3,102,518 or may be of other suitable construction. The clearance between the radial slot 34 and the associated apex seal 32 is exaggerated in the drawings solely for the sake of illustratlon.

As shown in FIGS. 1 and 3, the side seal assemblies according to this invention comprise for each rotor side face a plurality of side seal strips 36 which are disposed in grooves 38. As best shown in FIG. 3, each side seal strip 36 is biased in a direction outwardly of the groove by a wavy leaf spring 40 or other suitable biasing means. Each of the grooves 38 intersects, at one end, radial slot 34 for the apex seal 32 and, at the opposite end, the adjacent groove 38 near the latters intersection with radial slot 34. Each side seal strip 36 is dimensioned so that, in its associated groove, it extends, from one end in abutment at A against the next adjacent side seal strip 36, to radial groove 34 at the opposite end to engage the side surface of apex seal 32 at B. The side seal strips may be dimensioned so that the friction between each of the side seal strips 36 during rotation of rotor tends to urge each side seal strip into tight sealing abutment against the adjacent side seal strips at p A and that the clearances necessitated by manufacturing tolerances and thermal differential expansion are accounted for at the point B. With the necessary clearance being provided at B, the side seal strips 36 do not interfere with the motion of apex seals 32 within their respective radial slots 34.

leakage, at B, is very small as compared to the leakage path between the working chambers through the interstices between each end of apex seals 32 and the surface of end walls 15. Since a small leakage path at B is tolerable, the length of side seal strips 38 do not have to be exceedingly precise, thus rendering fabrication easier and less costly than the heretofore known side seal assemblies.

Another feature of the present invention is that the cutting of grooves 38 in the rotor faces 17 can terminate either in radial slot 34 or extend beyond the rotor periphery at 18' to thus eliminate the island of metal which is formed in the rotor at the apex area in the conventional side seal assemblies. This island of metal is vulnerable to damage in handling the rotor or overheating and deterioration during the operation of the engrne.

While it is preferable not to cut grooves 38 in the area 40 through to the peripheral wall surfaces 20 of rotor 16, each of the grooves may be cut at 40 and then filled with metal from peripheral wall surface 20 to a point of its intersection with the adjacent groove 38. The elimination or the filling in of grooves 38 at 40 functions to inhibit high pressure gases from leaking under side seal strips 36.

In the rotary piston mechanism 10D shown in FIG. 2, the side seal assemblies constitute a second embodiment of this invention in which each of the side seal assemblies comprise a plurality of side seal strips instead of single side seal strips 36 of the side seal assemblies shown in FIG. 1. Parts and components of the rotary piston mechanism 10D shown in FIG. 2 corresponding to the like parts and components of the rotary piston mechanism shown in FIG. 1 will be designated by the same reference number but with the suffix D added thereto.

As shown in FIG. 2, rotary piston mechanism 10D has, in each of the end faces of rotor 16D, the same side seal assembly consisting of side seal strips 36 as is shown in FIG. 1 and described with respect to rotary piston mechanism 10. In addition to side seal strips 36D, similar to side seal strips 36, the side seal assembly of FIG. 2 comprises a plurality of secondary side seal strips 46, similar to side seal strips 36D, disposed in grooves 48, similar to grooves 38D, and extending substantially parallel to the latter grooves. Each of the grooves 48 is located inwardly of the adjacent groove 38D and extends from the intersection, at one end, with a groove 38D to the intersection, at the opposite end, with an adjacent groove 48. Each of the secondary side seal strips 46 is dimensioned so that when placed in its associated groove 48 its one end abuts side seal strip 36D at C and its opposite end abuts an adjacent secondary side seal strip 48 at an area designated E. Similarly to side seal strips 36D and as illustrated in FIG. 3, secondary side-seal strips 46 are biased in a direction out of their associated grooves 48 to abut against the adjacent surface of end walls 15D. The secondary side seal strips 46 function to provide a continuous gaseous fluid seal which supplements the sealing effectiveness of side seal strips 36D and thereby further minimizes the leakage or blow-by of gas from working chambers 24D, 26D and 28D into the crankshaft area 30D.

The grooves 48 may be cut from one flank or peripheral surface 20D of the rotor to the opposite peripheral surface 20D and the unused portion 50 of the grooves may be filled with metal.

It is now believed readily apparent that this invention provides a novel end face sealing assembly for a rotary piston mechanism which avoids the problem inherent in conventional sealing assemblies of tolerance buildup between the hole for the apex pin, the outside diameter of the apex pin, the radial apex groove and the slot in the apex pin and the chordal notch in some pin assemblies, which require accurate fits to avoid excessive gas leakage. It is an end sealing assembly which does not require extreme accuracy in the fabrication of the seal strips with regard to their lengths. It is an assembly which is easier and less expensive to fabricate than conventional side sealing assemblies.

Although but two embodiments of the invention have been illustrated and described in detail, it is to be expressly understood that the invention is not limited thereto. Various changes can be made in the arrangement of parts without departing from the spirit and scope of the invention as the same will now be understood by those skilled in the art.

What is claimed is:

1. In a rotary piston mechanism comprising a rotor having opposite side faces and peripheral surfaces intersecting each other to form apex portions and which rotor is supported for rotation within a cavity formed by a peripheral wall and opposite end walls of a housing, an apex seal means at each apex portion to engage said peripheral wall, a side seal assembly for sealing the interstices between each side face of the rotor and the adjacent end wall of the housing and substantially isolating the working chambers formed by the rotor and said cavity, the side seal assembly comprises:

a. plurality of side seal strips carried in each end face of the rotor so as to abut each other and along their lengths abut the adjacent housing end wall;

b. each side seal strip is dimensioned in length so as to sealingly abut, at one end, the side of an adjacent side seal strip at a point near, but spaced from one of the apex seal means and, at the opposite end, capable of abutment against another of the apex seal means so that a substantially continuous seal is effected between the working chambers and the working chambers and the area adjacent the axis of rotation of the rotor.

2. The apparatus of claim 1 wherein each of said side seal strips is disposed in a groove in the rotor side face.

3. The apparatus of claim 1 wherein each of the apex seal means includes a seal plate means disposed in a radially extending slot in the apex portion of the rotor and wherein each of said side seal strips is disposed in a groove in the rotor side face which intersects, at one end a radial slot and intersects, at the opposite end, an adjacent side seal strip at a point adjacent the radial slot of the next adjacent apex seal means.

4. The apparatus of claim 3 wherein a biasing means is provided to resiliently urge each of said side seal strips in a direction out of their respective grooves and against the adjacent side wall.

5. The apparatus of claim 2 wherein each groove extends, from intersection with one peripheral surface of the rotor, in the general direction of an adjacent peripheral surface to intersection at the opposite end with another adjacent peripheral surface.

6. The apparatus of claim 2 in which the portions of the grooves not occupied by side seal strips are filled.

7. The apparatus of claim 3 wherein each of said grooves extends beyond its intersection with the radially extending slot for the apex seal means to intersection with the peripheral surface at the intersection of the slot and said peripheral surface.

8. The apparatus of claim 1 wherein a plurality of second side seal strips are carried in each end face of the rotor so that each of the second side seal strips abuts at its ends a first-mentioned side seal strip and an adjacent second side seal strip to thereby form a secondary continuous seal adjacent the continuous seal formed by said first-mentioned side seal strips.

9. The apparatus of claim 8 wherein each of said second side seal strips extends substantially parallel to a first-mentioned side seal strip.

10. The apparatus of claim 8 wherein each of the secondary side seal strips is disposed in a groove in the rotor face which groove extends from intersection, at one end, with a peripheral surface of the rotor to the intersection, at the opposite end, with an adjacent peripheral surface.

11. The apparatus of claim 10 wherein the portions of each groove not occupied by a second side seal strip is filled. 

1. In a rotary piston mechanism comprising a rotor having opposite side faces and peripheral surfaces intersecting each other to form apex portions and which rotor is supported for rotation within a cavity formed by a peripheral wall and opposite end walls of a housing, an apex seal means at each apex portion to engage said peripheral wall, a side seal assembly for sealing the interstices between each side face of the rotor and the adjacent end wall of the housing and substantially isolating the working chambers formed by the rotor and said cavity, the side seal assembly comprises: a. plurality of side seal strips carried in each end face of the rotor so as to abut each other and along their lengths abut the adjacent housing end wall; b. each side seal strip is dimensioned in length so as to sealingly abut, at one end, the side of an adjacent side seal strip at a point near, but spaced from one of the apex seal means and, at the opposite end, capable of abutment against another of the apex seal means so that a substantially continuous seal is effected between the working chambers and the working chambers and the area adjacent the axis of rotation of the rotor.
 2. The apparatus of claim 1 wherein each of said side seal strips is disposed in a groove in the rotor side face.
 3. The apparatus of claim 1 wherein each of the apex seal means includes a seal plate means disposed in a radially extending slot in the apex portion of the rotor and wherein each of said side seal strips is disposed in a groove in the rotor side face which intersects, at one end a radial slot and intersects, at the opposite end, an adjacent side seal strip at a point adjacent the radial slot of the next adjacent apex seal means.
 4. The apparatus of claim 3 wherein a biasing means is provided to resiliently urge each of said side seal strips in a direction out of their respective grooves and against the adjacent side wall.
 5. The apparatus of claim 2 wherein each groove extends, from intersection with one peripheral surface of the rotor, in the general direction of an adjacent peripheral surface to intersection at the opposite end with another adjacent peripheral surface.
 6. The apparatus of claim 2 in which the portions of the grooves not occupied by side seal strips are filled.
 7. The apparatus of claim 3 wherein each of said grooves extends beyond its intersection with the radially extending slot for the apex seal means to intersection with the peripheral surface at the intersection of the slot and said peripheral surface.
 8. The apparatus of claim 1 wherein a plurality of second side seal strips are carried in each end face of the rotor so that each of the second side seal strips abuts at its ends a first-mentioned side seal strip and an adjacent second side seal strip to thereby form a secondary continuous seal adjacent the continuous seal formed by said first-mentioned side seal strips.
 9. The apparatus of claim 8 wherein each of said second side seal strips extends substantially parallel to a first-mentioned side seal strip.
 10. The apparatus of claim 8 wherein each of the secondary side seal strips is disposed in a groove in the rotor face which groove extends from intersection, at one end, with a peripheral surface of the rotor to the intersection, at the opposite end, with an adjacent peripheral surface.
 11. The apparatus of claim 10 wherein the portions of each groove not occupied by a second side seal strip is filled. 